E10.7 In Worked Example 10.1, make the process method a default method of the Se

Question

E10.7 In Worked Example 10.1, make the process method a default method of the Sequence
interface.

Worked Example 10.1 (four classes and an interface)

1)

/**
This class analyzes the distribution of the last digit of values
from a sequence.
*/
public class LastDigitDistribution
{
private int[] counters;

/**
Constructs a distribution whose counters are set to zero.
*/
public LastDigitDistribution()
{
counters = new int[10];
}

/**
Processes values from this sequence.
@param seq the sequence from which to obtain the values
@param valuesToProcess the number of values to process
*/
public void process(Sequence seq, int valuesToProcess)
{
for (int i = 1; i <= valuesToProcess; i++)
{
int value = seq.next();
int lastDigit = value % 10;
counters[lastDigit]++;
}
}

/**
Displays the counter values of this distribution.
*/
public void display()
{
for (int i = 0; i < counters.length; i++)
{
System.out.println(i + ": " + counters[i]);
}
}
}

2)

public class RandomSequence implements Sequence
{
public int next()
{
return (int) (Integer.MAX_VALUE * Math.random());
}
}

3)

public interface Sequence
{
int next();

public void process(Sequence seq, int valuesToProcess);
}

4)

public class SequenceDemo
{
public static void main(String[] args)
{
LastDigitDistribution dist1 = new LastDigitDistribution();
dist1.process(new SquareSequence(), 1000);
dist1.display();
System.out.println();

LastDigitDistribution dist2 = new LastDigitDistribution();
dist2.process(new RandomSequence(), 1000);
dist2.display();
}
}

5)

public class SquareSequence implements Sequence
{
private int n;

public int next()
{
n++;
return n * n;
}
}

Explanation / Answer

Note:- in order to make a process as default process we need to define the method in the interface with default keyword.
USE OF DEFAULT METHOD :- default method will be executed,if the class which interfaces won't define the method.Then,in that case default method will be executed

Changes:- I have added the given method itself as default method for process and the changes made are in BOLD format

Code:-

1)

/**
This class analyzes the distribution of the last digit of values
from a sequence.
*/
public class LastDigitDistribution
{
private int[] counters;

/**
Constructs a distribution whose counters are set to zero.
*/
public LastDigitDistribution()
{
counters = new int[10];
}

/**
Displays the counter values of this distribution.
*/
public void display()
{
for (int i = 0; i < counters.length; i++)
{
System.out.println(i + ": " + counters[i]);
}
}
}

2)

public class RandomSequence implements Sequence
{
public int next()
{
return (int) (Integer.MAX_VALUE * Math.random());
}
}

3)

public interface Sequence
{
int next();

default public void process(Sequence seq, int valuesToProcess){

  /**
Processes values from this sequence.
@param seq the sequence from which to obtain the values
@param valuesToProcess the number of values to process
*/
   for (int i = 1; i <= valuesToProcess; i++)
{
int value = seq.next();
int lastDigit = value % 10;
counters[lastDigit]++;
}
}

4)

public class SequenceDemo
{
public static void main(String[] args)
{
LastDigitDistribution dist1 = new LastDigitDistribution();
dist1.process(new SquareSequence(), 1000);
dist1.display();
System.out.println();

LastDigitDistribution dist2 = new LastDigitDistribution();
dist2.process(new RandomSequence(), 1000);
dist2.display();
}
}

5)

public class SquareSequence implements Sequence
{
private int n;

public int next()
{
n++;
return n * n;
}
}

Related Questions

Navigate

• Browse (All)
• Browse E
• Subjects

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.